JP2528261Y2 - Thrust bearing structure of camshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to a camshaft thrust bearing structure.
In particular, the present invention relates to a pair of intake and exhaust camshaft thrust bearing structures provided in an automobile DOHC type engine.

(Prior art)

Generally, in a valve operating mechanism of a DOHC type engine for an automobile, a pair of intake and exhaust camshafts mesh with each other in order to reduce the size and improve the performance of the engine.
A technique of providing a pair of timing gears and interlockingly driving a camshaft via these timing gears is often used.

Usually, in the above-described valve mechanism, in order to receive a thrust load acting on the camshaft due to meshing of the timing gear, a camshaft close to the timing gear is used, for example, as described in Japanese Utility Model Application Laid-Open No. 62-76205. An annular thrust groove is provided in a bearing portion of the camshaft, a thrust regulating portion accommodated in the thrust groove is provided in a journal portion of the cam shaft, and a thrust bearing structure having an oil passage for supplying oil to the bearing portion is provided. .

In the above-described bearing structure, generally, when cutting, the clearance of the bearing portion on the timing gear side from the thrust groove and the clearance of the bearing portion on the side opposite to the timing gear from the thrust groove are set to be equal, and from the oil passage to the bearing portion. The supplied oil leaks outside through the clearance.

On the other hand, in order to lubricate the timing gear,
JP-A-62-118 discloses an annular member having an oil hole attached to a camshaft and communicating with an oil passage formed in the camshaft, a nozzle for supplying oil from the oil hole to a meshing portion of a timing gear, and the like. Lubricating devices have been proposed.

[Problems to be solved by the invention]

The lubricating device described in the above publication has a problem that the number of components is large, the structure is complicated, and the manufacturing cost is high. In addition, there is a problem that a space for mounting a lubrication device is required.

An object of the present invention is to provide a camshaft thrust bearing structure that can lubricate a timing gear with a simple configuration.

[Means for solving the problem]

The camshaft thrust bearing structure according to the present invention is provided with a pair of timing gears meshing with each other on a pair of intake and exhaust camshafts, and an annular camshaft bearing portion near the timing gear. In a camshaft thrust bearing structure provided with a thrust groove and a thrust regulating portion accommodated in the thrust groove in a journal portion of the camshaft and provided with an oil passage for supplying oil to the bearing portion, a timing gear is provided from the thrust groove. The clearance between the bearing portion and the journal portion on the side opposite to the thrust groove is set to be larger than the clearance between the bearing portion and the journal portion on the side opposite to the timing gear.

[Action]

In the camshaft thrust bearing structure according to the present invention, the clearance between the bearing portion and the journal portion on the timing gear side of the thrust groove is between the bearing portion and the journal portion on the anti-timing gear side of the thrust groove. Since the clearance is set to be larger than the clearance, the oil supplied to the thrust groove leaks more from the clearance between the bearing portion and the journal portion on the timing gear side than the thrust groove, and is supplied to the timing gear. The oil is supplied to the tooth tip by the rotation of the tooth, and lubricates the tooth tip. Further, if an oil reservoir for receiving the oil supplied to the timing gear is provided below the timing gear, the timing gear can always be lubricated with oil, and the lubricity of the timing gear can be further improved.

[Effect of the invention]

According to the camshaft bearing structure according to the present invention, the clearance between the bearing portion and the journal portion in the timing gear in the timing gear is shifted from the thrust groove to the side opposite to the timing gear in relation to the thrust groove as described in the above section. Simple lubrication of the clearance between the bearing and the journal in the above, the lubrication of the timing gear can be ensured, and there is no special member for lubricating the timing gear, so miniaturization is achieved. Can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In this embodiment, the present invention is applied to a thrust bearing structure of an intake camshaft and an exhaust camshaft of a V-type 6-cylinder DOHC engine (hereinafter, referred to as an engine) for an automobile. Since the intake camshaft and the exhaust camshaft have the same configuration in the left and right banks of the engine, the right bank will be described below.

As shown in FIGS. 1 to 3, three cylinders 2 are provided in the front-rear direction on the cylinder block 1 of the right bank R formed in an inclined shape.
The cylinder head 3 is fixed by a plurality of head bolts 4, and a pair of front and rear intake ports and a pair of front and rear exhaust ports are provided at a portion corresponding to each cylinder 2 of the cylinder head 3, and a pair of front and rear intake ports are provided. A pair of intake valves for opening and closing ports and a pair of exhaust valves for opening and closing a pair of front and rear exhaust ports are provided, and an intake camshaft 5 and a front side of the intake camshaft 5 are provided above the cylinder head 3. A slightly longer exhaust camshaft 6 is provided in parallel in the front-rear direction.

A cam 7 corresponding to an intake valve is formed on the intake camshaft 5. A front end of the intake camshaft 5 is brought into contact with a front end face of the timing gear 8 by a timing gear 8 composed of a helical gear and a spring member 9. A friction gear 10 urged to be in contact with and rotatable relative to the timing gear 8 is fixed.

On the other hand, a cam 11 corresponding to an exhaust valve is formed on the exhaust camshaft 6, and a portion slightly behind the front end of the exhaust camshaft 6 is meshed with the timing gear 8 and has a timing gear having the same number of teeth. A pulley 13 is attached to the front end of the exhaust camshaft 6, and the pulley 13 is linked to a crankshaft via a timing belt 14.

As shown in FIG. 1, an intermediate portion in the front-rear direction of the intake camshaft 5 and the exhaust camshaft 6 is a journal portion 15 between the cams 7 and a journal portion 16 between the cams 11 corresponding to each cylinder 2. A front end of the intake camshaft 5 is rotatably supported by the cylinder head 3 and a timing gear 8.
The journal shaft 17 is rotatably supported by the cylinder head 3 near the rear side. The front end of the exhaust camshaft 6 is connected to the journal portions 18 near the front side and the rear side of the timing gear 12.
The cylinder 19 is rotatably supported by the cylinder head 3, and the lower portions of the timing gears 8 and 12 are accommodated in accommodation grooves 20 formed in the cylinder head 3. Reference numeral 21 denotes a bearing cap,
Reference numeral 22 denotes a head cover, reference numeral 23 denotes an exhaust port, and reference numeral 24 denotes a valve shaft of an exhaust valve.

Next, a thrust load acts on the intake camshaft 5 and the exhaust camshaft 6 as the timing gears 8 and 12 mesh with each other and rotate. A thrust bearing structure for receiving the thrust load will be described. .
Since the above-described thrust bearing structure is the same for the intake camshaft 5 and the exhaust camshaft 6, the structure of the exhaust camshaft 6 will be described.

The cylinder head 3 near the rear side of the timing gear 12
And a bearing cap 26 fixed to the cylinder head 3 constitute a bearing portion 25 for supporting the journal portion 19 of the exhaust camshaft 6, and the bearing portion 25 has an annular thrust groove 27 formed therein. An annular thrust restricting portion 28 is formed in the portion 19 so as to fit in the thrust groove 27. The cylinder head 3 below the thrust groove 27 communicates with the thrust groove 27 and receives an oil from an oil supply source (not shown). An oil supply path 30 through which the lubricating oil 29 is pumped through the gallery is formed.

By providing the annular thrust groove 27 and the thrust restricting portion 28 in this manner, a thrust load acting on the exhaust camshaft 6 can be received by the thrust groove 27 via the thrust restricting portion 28.

The oil 29 supplied to the thrust groove 27 is transferred to the journal 16.
An oil passage 32 is formed in the thrust restricting portion 28 to connect the thrust groove 27 to the oil passage 31 formed in the front-rear direction in the exhaust camshaft 6 so as to supply the oil to the thrust groove 27. The supplied oil 29 is supplied to the oil passage 31 via the oil passage 32, and is supplied to the journal 16 via the oil passage 33 branched from the oil passage 31.
・ Supplied to 18.

On the other hand, the clearance between the inner peripheral surface of the bearing portion 25 and the outer peripheral surface of the journal portion 19 on the front side of the thrust regulating portion 28, that is, on the timing gear 12 side, and on the rear side of the thrust regulating portion 28, Oil 29 leaking from the thrust groove 27 is supplied through a clearance between the inner peripheral surface of the bearing portion 25 on the side opposite to the timing gear and the outer peripheral surface of the journal portion 19.

The outer peripheral surface of the journal portion 19 on the front side of the thrust restricting portion 28 is additionally subjected to cutting to make the diameter of the outer peripheral surface slightly smaller than the diameter of the outer peripheral surface of the journal portion 19 on the rear side of the thrust restricting portion 28. Thus, the clearance (for example, 0.12 mm) of the bearing 25 on the timing gear side is set to be larger than the clearance (for example, 0.06 mm) of the bearing 25 on the side opposite to the timing. However, the clearance is obtained by subtracting the diameter of the outer peripheral surface of the journal portion 19 from the diameter of the inner peripheral surface of the bearing portion 25.

The clearance on the timing gear side of the bearing 25 of the intake camshaft 5 and the clearance on the opposite timing gear side are set in the same manner.

By setting the clearance in this way, the oil 29 in the thrust groove 27 leaks more from the clearance on the timing gear side than from the clearance on the opposite timing gear side, and is supplied to the timing gear 12 side. Is supplied to the tip of the timing gear 13 by the rotation of the gaming gear 12 to lubricate the tip, and the third
As shown in the figure, the timing gear 12 is stored in an oil reservoir 34 formed in the accommodation groove 20, and is lubricated by the oil reservoir 34,
The timing gear 8 meshing with the timing gear 12 is also lubricated. The oil 29 in the oil reservoir 34
Is returned to the oil pan via the return oil passage 35.

As described above, the timing gears 8 and 12 are reliably lubricated with a simple structure in which the clearance on the timing gear side of the thrust groove 27 of the bearing portion 25 is set to be larger than the clearance on the side opposite to the timing gear side of the thrust groove 27. I can do it. In addition, since no special member for lubricating the timing gears 8 and 12 is provided, the size can be reduced.

The clearance on the timing gear side of the bearing 25 may be set larger than the clearance on the opposite timing gear side by processing the cylinder head 3 and the bearing cap 26. Further, it is also possible to form an oil reservoir on the lower end side of the timing gear 8. In addition, it goes without saying that the above-mentioned thrust bearing structure can be applied to an in-line cylinder type DOHC engine.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a plan view of a right bank, FIG. 2 is a sectional view taken along the line II-II of FIG.
FIG. 3 is a sectional view taken along the line III-III of FIG. 5 ... Camshaft for intake, 6 ... Camshaft for exhaust, 8/12 Timing gear, 17/19 ... Journal part, 25 ... Bearing part, 27 ... Thrust groove, 28 ... Thrust regulating part , 30 ... Oil supply passage.

Claims (1)

(57) [Scope of request for utility model registration] A pair of intake and exhaust camshafts are provided with a pair of timing gears meshing with each other, and an annular thrust groove is provided in a bearing portion of the camshaft adjacent to the timing gears. In a camshaft thrust bearing structure in which a thrust regulating portion accommodated in a thrust groove is provided in a journal portion of the camshaft and an oil passage for supplying oil to the bearing portion, a bearing portion (25) on a timing gear side of the thrust groove is provided. And the clearance between the journal (19)
A thrust bearing structure for a camshaft, characterized in that the clearance is set to be larger than the clearance between the bearing portion (25) and the journal portion (19) on the side opposite to the timing gear than the thrust groove.